The disclosure provides seven integrated methods for the chemical sequestration of carbon dioxide (CO.sub.2), nitric oxide (NO), nitrogen dioxide (NO.sub.2) (collectively NO.sub.2, where x=1, 2) and sulfur dioxide (SO.sub.2) using closed loop technology. The methods recycle process reagents and mass balance consumable reagents that can be made using electrochemical separation of sodium chloride (NaCl) or potassium chloride (KCl). The technology applies to marine and terrestrial exhaust gas sources for CO.sub.2, NO.sub.x and SO.sub.2. The integrated technology combines compatible and green processes that capture and/or convert CO.sub.2, NO.sub.x and SO.sub.2 into compounds that enhance the environment, many with commercial value.

The present invention relates to a method for preparing lithium hydroxide, comprising subjecting an aqueous composition (A), comprising lithium sulfate and sodium sulfate, to bipolar membrane electrodialysis; said step of bipolar membrane electrodialysis comprises processing in an electrodialyser comprising at least one electrodialysis cell (200) comprising a first compartment (220), supplied with water and delimited between a first bipolar membrane (250) and an anionic central membrane (230), and a second compartment (210), supplied with said aqueous composition (A) and delimited between said anionic central membrane (230) and a second bipolar membrane (240), then recovering, from said at least one electrodialysis cell (200), an aqueous composition (B) comprising lithium hydroxide and sodium sulfate, and subjecting it to a crystallisation step in order to prepare a salt.

Methods of producing sodium hydroxide (NaOH) or lithium hydroxide (LiOH), and sulfuric acid (H.sub.2SO.sub.4), include generating sodium sulfate (Na.sub.2SO.sub.4) or lithium sulfate (Li.sub.2SO.sub.4) from battery manufacturing and recycling and converting the generated Na.sub.2SO.sub.4 or Li.sub.2SO.sub.4 to NaOH, LiOH, and H.sub.2SO.sub.4 via an electrochemical salt-splitting process. The processing steps can be carried out in a closed system such that the generated Na.sub.2SO.sub.4 or Li.sub.2SO.sub.4 can be used in the conversion process with optional purification steps. In particular, the LiOH, NaOH, and Na.sub.2SO.sub.4 are recycled into battery recycling or battery manufacturing processes.

Methods of producing sodium hydroxide (NaOH) or lithium hydroxide (LiOH), and sulfuric acid (H.sub.2SO.sub.4), include generating sodium sulfate (Na.sub.2SO.sub.4) or lithium sulfate (Li.sub.2SO.sub.4) from battery manufacturing and recycling and converting the generated Na.sub.2SO.sub.4 or Li.sub.2SO.sub.4 to NaOH, LiOH, and H.sub.2SO.sub.4 via an electrochemical salt-splitting process. The processing steps can be carried out in a closed system such that the generated Na.sub.2SO.sub.4 or Li.sub.2SO.sub.4 can be used in the conversion process with optional purification steps. In particular, the LiOH, NaOH, and Na.sub.2SO.sub.4 are recycled into battery recycling or battery manufacturing processes.

A process for the recovery of sodium sulfate from water, in particular from water deriving from a silica manufacturing process.

A process for the recovery of sodium sulfate from water, in particular from water deriving from a silica manufacturing process.

A method for recovering lithium from low-content extraction tailwater and recycling extraction tailwater is provided. The disclosure is characterized that recovery of lithium from lithium-containing extraction tailwater is achieved by adding calcium to remove fluorine, carrying out evaporative crystallization and precipitating lithium salts. Recycle of extraction tailwater is achieved by adopting the following steps: in the lithium-containing extraction tailwater, adding calcium to remove fluorine, carrying out evaporative crystallization, recovering condensate water, precipitating a lithium salt and recycling mother liquor. According to the disclosure, lithium is recovered from low-content extraction tailwater via enrichment and sodium sulfate and distilled water therein are incidentally recovered, so that zero release of battery waste treatment wastewater is achieved.

A method for recovering lithium from low-content extraction tailwater and recycling extraction tailwater is provided. The disclosure is characterized that recovery of lithium from lithium-containing extraction tailwater is achieved by adding calcium to remove fluorine, carrying out evaporative crystallization and precipitating lithium salts. Recycle of extraction tailwater is achieved by adopting the following steps: in the lithium-containing extraction tailwater, adding calcium to remove fluorine, carrying out evaporative crystallization, recovering condensate water, precipitating a lithium salt and recycling mother liquor. According to the disclosure, lithium is recovered from low-content extraction tailwater via enrichment and sodium sulfate and distilled water therein are incidentally recovered, so that zero release of battery waste treatment wastewater is achieved.

The present application pertains to processes producing oxides using a weak acid intermediate. In one embodiment a material comprising calcium carbonate is reacted with a solution comprising aqueous carboxylic acid to form a gas comprising carbon dioxide and a solution comprising aqueous calcium carboxylate. The solution comprising aqueous calcium carboxylate is reacted with sodium sulfate to form a solution comprising aqueous sodium carboxylate and a solid comprising calcium sulfate. The solution comprising aqueous sodium carboxylate is reacted with sulfur dioxide to form sodium sulfite and an aqueous carboxylic acid. The sodium sulfite is separated from said aqueous carboxylic acid and reacted to form a solid comprising calcium sulfite which is decomposed to form calcium oxide and sulfur dioxide.

The present invention relates to a method for producing a potassium sulfate containing fertilizer composition from a sodium sulfate containing residue process stream of a battery manufacturing facility, battery recycling facility, or steel production plant, wherein residue process stream from a battery manufacturing facility, battery recycling facility, or steel production plant is provided; optionally water is provided; potassium chloride is provided; and a reaction mixture is provided comprising said optional water, potassium chloride and residue process stream, and is allowed to react, wherein potassium sulfate is obtained.